Still, the chairman of the Senate Foreign Relations subcommittee on European Affairs said he thinks there is strong bipartisan support for "a tough sanctions regime" on Capitol Hill.

“Ultimately, if Europe and the United States join together in some pretty crippling economic sanctions, I don't know whether it's gonna convince him to leave Crimea because that's — that's a bad sort of historical and psychological connection to the region. But it certainly will change his behavior if he ever thinks about this again,” Murphy said on MSNBC’s “Morning Joe.”

The Obama administration is now weighing how to handle Russia’s invasion of Crimea, a semi-autonomous peninsula in Ukraine. Secretary of State John Kerry will travel to Ukraine to meet with officials there on Tuesday.

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Murphy said he hopes Kerry goes not to just offer political support but economic support. The International Monetary Fund, with U.S. backing, he said, should provide a “pretty big aid package” that could cost around $15 billion-$20 billion.

“If there was a combined sanctioning of the three largest Russian banks from the United States and from Europe, it would effectively shut down Russia's economy,” Murphy said.

It’s in Europe’s interest to “draw a hard line,” said Murphy.

Murphy has been closely following events in Ukraine, which he visited with Sen. John McCain (R-Ariz.) in December. Last month, Murphy and McCain worked on legislation that would have imposed sanctions against Ukraine when Viktor Yanukovych was still president, but he has since been ousted.

After conversations with Republicans and Democrats over the last three days, Murphy said Congress “will pretty easily join together" over Russia's incursion into Ukraine.